1. Field of the Invention
This invention relates to a synthetic resin rivet, which comprises a rivet body and a pin, the rivet body being adapted to increase in diameter with forced insertion of the pin thereinto.
2. Description of the Prior Art
FIG. 10 shows a well-known synthetic resin rivet 5 which comprises a rivet body 3 having a hollow cylindrical portion 1 and an integral disk-like flange portion 2 extending radially outwardly from the upper end of the cylindrical portion 1 and a cylindrical pin 4 for spreading the hollow cylindrical portion 1 of the rivet body 3 in the radially outward direction as it is inserted into the cylindrical portion 1. (Japanese Utility Model Publication No. Sho 44-28336)
In this prior art rivet 5, however, the rivet body 3 is formed as a one-piece molding of a resin having a comparatively high degree of hardness, such as, for example, nylon. Therefore, in order to insert the pin 4 into the cylindrical portion 1 of the rivet body 3, a very high insertion force is required, meaning that the operability of this rivet is rather inferior.
Furthermore, since the rivet body 3 has a high degree of hardness, its cylindrical portion 1 does not readily spread uniformly. Therefore, the sealing property of this rivet is inferior. Furthermore, the cylindrical portion 1 of the rivet body 3 and the end of the pin 4 are liable to crack when the pin 4 is inserted.